Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B35/00—Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws
  • F16B35/04—Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws with specially-shaped head or shaft in order to fix the bolt on or in an object
  • F16B35/06—Specially-shaped heads
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B19/00—Bolts without screw-thread; Pins, including deformable elements; Rivets
  • F16B19/04—Rivets; Spigots or the like fastened by riveting
  • F16B19/06—Solid rivets made in one piece

Definitions

• the present invention relates to very small headed push-in fasteners of the type produced by Penn Engineering & Manufacturing Corp. known as TackPins and TackScrews. More specifically, it relates to a Tack Pin or a Tack Screw with a Belleville head that provides the functionality of a Bellville washer without requiring a separate part.
• the attachment of two members can be made in a number of different ways. Some attachment methods such as adhesives, glues, or welding can form a strong bond between the members without generating any squeezing or clamping force between the members. Fasteners such as a typical rivet or tack pins / screws, also do not create a clamping force on the members. When a clamping force is desired, screws are a common method of achieving this.
• the yield force of the female threads is calculated as the yield stress of the thread in the bottom panel as shown in Figure 1, multiplied by the area of the thread that is in shear.
• the area of the thread in shear is the cylindrical surface per thread that would be left if a screw were to cut the threads out if pulled or pushed vertically. Because the effect of the thread helix on this area is very small, the area of thread in shear can be simplified to be the number of threads in shear multiplied by the cylindrical area of one thread.
• Tightening the screw causes a tension force in the screw. That is to say the part of the screw between the underside of the head and the top of the engaging threaded member. Part of the clamp load generated stretches the screw like a spring. Hooke's Law describes the change in length of the screw. The shorter a screw is made, the less capable it is of stretching. Hooke's Law applies equally for the top panel, which is compressed by the clamp load. The force experienced by the top sheet is equal to the clamp load. In the case shown in Figure 1, the panel is thin which also tends to limit the potential compression. It is the application of a hard screw into a thin soft enclosure that enables a clinch attachment to compete very well against a screw thread.
• FIG. 2 another example of a prior art fastener is depicted. Since a tack pin or a tack screw is pressed in, and is not in tension during installation, it can provide little or no clamp load. The compression of the top sheet can provide a component of clamp, however the situation is slightly different from the case of a screw.
• both will change in length (shorten or compress) per Hooke's law. As long as the parts were not crushed beyond their yield points, both will relax (attempt to return to their original lengths) when the installation load is removed.
• top sheet might be a gasket material like rubber.
• the yielding of the undercut in the bottom sheet is the overriding maximum clamp load allowable for a tack pin / screw if the top sheet has the capability of generating such a force.
• Clinching Tack pins / screws are an excellent alternative to very small screws, and provide numerous advantages over a screw, including:
• Tack pins / screws do not require a thread locking patch and are inherently non-loosening
• Tack pins / screws have very thin heads and permit thinner design forms than screws which require thicker heads due to the drivers required in the head.
• Tack Pins / Screws Some shortcomings of Tack Pins / Screws are: 1) Little or no clamp load (while it is minimal, a short screw does provide a bit of clamp load)
• tack pins and tack screws listed above are all overcome by a novel design change that would incorporate the design of a Bellville type spring into the head of the tack pin or tack screw. It is believed that with the spring head design improvement, the tack pin or screw can provide all the advantages of a short screw, with the added benefits afforded by ordinary tack pins where because of their miniature size adding a separate washer is not practical.
• the spring head structure can directly address the clamp load issue as well as adding tolerance to the installation pressing distance, easing the requirement of a perfect installation.
• the fastener comprises a head having a radially extending cone-shaped flange being the largest diameter of the fastener and having an uninterrupted peripheral circular surface adapted to resiliently deflect upwardly against the top element upon application of a downward installation force.
• the fastener has a shank which utilizes engagement means such as helical threads or a clinch undercut.
• a secondary object is to devise a screw design that incorporates a Bellville washer into the head for the benefit of preventing loss of preload in the screw. It is a further objective to accomplish these advantages while also providing economy of
• Figures 1 and 2 are cross- sectional views of prior art fasteners.
• Figure 3 is a cross-sectional view of three embodiments of the invention. Description of the Preferred Embodiments
• FIG 3 three embodiments of the fastener of the invention are shown in side-by-side comparison with a Belleville washer. Any one of the embodiments is utilized to create an assembly in place of the fasteners of the prior art shown in Figures 1 or 2 which join a top sheet to a bottom sheet.
• Each of the embodiments has a head which includes a cone-shaped flange which approximates the structure and performance of a Belleville washer shown at the far left.
• a Belleville washer creates force opposite to the direction of its compression. This figure depicts how a Belleville washer can be incorporated into the head of a tack pin, a tack screw, and a micro screw.
• the maximum force capability of a Belleville spring is given by equations that can be sourced from website Spring-I-Pedia at: http://springipedia.com/be11eville- washers-formulas.asp .
• the periphery of the cone-shaped flange Upon installation, the periphery of the cone-shaped flange deflects resiliently upward as it forcefully contacts the top sheet. By the resilient nature of its material a continual biasing force is applied so that a residual clamp load is maintained.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Bolts, Nuts, And Washers (AREA)
• Connection Of Plates (AREA)
• Dowels (AREA)
• Insertion Pins And Rivets (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (1)

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Citations (11)

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• 2014
  • 2014-08-28 WO PCT/US2014/053048 patent/WO2015031557A1/en active Application Filing
  • 2014-08-28 CA CA2922677A patent/CA2922677C/en active Active
  • 2014-08-28 CN CN201480058990.2A patent/CN105683594B/zh active Active
  • 2014-08-28 TW TW103129672A patent/TWI620877B/zh active
  • 2014-08-28 US US14/471,020 patent/US9816545B2/en active Active
  • 2014-08-28 JP JP2016537835A patent/JP6421187B2/ja active Active
  • 2014-08-28 EP EP14840744.8A patent/EP3039306B1/en active Active
  • 2014-08-28 HU HUE14840744A patent/HUE034868T2/hu unknown
  • 2014-08-28 MY MYPI2016700634A patent/MY180864A/en unknown
  • 2014-08-28 MX MX2016002475A patent/MX371271B/es active IP Right Grant
  • 2014-08-28 PL PL14840744T patent/PL3039306T3/pl unknown
  • 2014-08-28 SG SG11201601411UA patent/SG11201601411UA/en unknown

Patent Citations (11)

Non-Patent Citations (1)

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